Mount arrangement and interchangeable lens unit for photographic camera

ABSTRACT

A mount arrangement for a photographic camera which is capable of automatic diaphragm control and automatic focusing includes electrical contacts for transmission of electrical signals between a camera body and an interchangeable lens unit, and mechanical transmission members for the automatic diaphragm control and the automatic focusing and positioning member and recess on and at inner periphery of mount members of the camera body and the lens unit so as not to interfere with each other during the start and the course of the mounting of the lens unit onto the camera body through a bayonet mount device.

This application is a division of application ser. no. 891,999, filedJuly 31, 1986, which is a continuation of U.S. Ser. No. 748,647, filed6/25/85. Now U.S. Pat. No. 4,620,780, which is a continuation of U.S.Ser. No. 645,939, filed 8/30/84. Now U.S. Pat. No. 4,536,071.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a mount arrangement for a lensinterchangeable type photographic camera which is capable of bothautomatic diaphragm control and automatic focusing and also relates toan interchangeable lens unit for the camera.

2. Prior Art

In recent lens interchangeable photographic cameras, various means areneeded on and/or in the vicinity of mount members of a camera body andan interchangeable lens unit for transmission of mechanical andelectrical signals between the camera body and the interchangeable lensunit with multiplication and improvement of camera functions.Particularly, in a lens interchangeable photographic camera which isadapted to effect automatic diaphragm control and automatic focusing bysignals from the camera body, a diaphragm interlocked mechanism, anautomatic focusing drive mechanism and electrical contact means forsupplying and receiving various electrical signals are needed on and/orin the vicinity of the mount members of the camera body and the lensunit in addition to a positioning mechanism for positioning the lensunit relative to the camera body with the lens unit mounted on thecamera body. Thus, the diaphragm interlocked mechanism, the automaticfocusing drive mechanism and the electrical contact means are composedof a member or members provided on or in the vicinity of the mountmember of the lens unit and a corresponding member or members providedon or in the vicinity of the mount member of the camera body,respectively. However, as there is not a large space permitting theprovision of these members on and/or in the vicinity of the mountmembers without exposing these members to the outside of the camera bodyand the lens unit and without intercepting the optical path forphotographing, it becomes necessary to determine the positions of thesemembers rationally on the whole so that no interference occurs betweenthe members on the side of the lens unit and the members on the side ofthe camera body upon the mounting and demounting of the lens unit on andfrom the camera body and so that the corresponding members are coupledwith or brought into contact with one another without fault.Conventionally, a bayonet mount device which couples the lens unit withthe camera body through a predetermined angle rotation of the lens unitrelative to the camera body is used for the coupling, and therefore thismust be also taken into consideration to determine the positions ofthose members on and/or in the vicinity of the mount members of thecamera body and the lens unit.

Hitherto, a photographic camera of the above mentioned type capable ofautomatic diaphragm control and automatic focusing by signals from acamera body is known by Japanese magazine, the Nippon Camera, December1982, page 280. With this camera, a positioning member is located at anupper and right side portion of the mount member of the camera body asviewed from the front of the camera body and urged radially inwardly toengage a positioning recess formed on a bayonet claw located at an upperleft side portion of the amount member of the lens unit as viewed fromthe rear of the lens unit with the mounting of the lens unit on thecamera body completed. A diaphragm control member to be coupled with adiaphragm interlocked member of the lens unit for automatic diaphragmcontrol is located at the inner peripheral side of a lower-most portionof the mount member of the camera body with its end retreated from themount surface of the mount member while the diaphragm interlocked memberis located at the inner peripheral side of a lower-most portion of themount member of the lens unit with its rear end projecting from themount surface of the mount member. Electrical contacts of the camerabody to be brought into contact with electrical contacts of the lensunit are located on the mount surface of the mount member of the camerabody at an upper and lower left side portion of the mount member asviewed from the front of the camera body while the electrical contactsof the lens unit are located on the mount surface of the mount member ofthe lens unit at an upper and lower right side portion of the mountmember as viewed from the rear of the lens unit with the mounting of thelens unit on the camera body completed. The electrical contacts of thelens unit are normally in a projecting state projecting slightly fromthe mount surface of the mount member of the lens unit respectively.Furthermore, with the camera, a driving shaft of the camera body to becoupled with a driven shaft of the lens unit for automatic focusing islocated on the mount surface of the mount member of the camera body atan immediate left side portion of the mount member as viewed from thefront of the camera body while the driven shaft is located on the mountsurface of the mount member of the lens unit at an immediate right sideportion of the mount member as viewed from the rear of the lens unit.

Other prior arts disclosing a mount arrangement which includes variousmeans arranged on and/or in the vicinity of mount members of a camerabody and an interchangeable lens unit for transmission of mechanical andelectrical signals between the camera body and the interchangeable lensunit are U.S. Pat. Nos. 4,104,649, 4,432,627, 4,357,089 and 4,449,807,Japanese Patent laid open publication Nos. Sho. 58-83824 and Sho.55-120022 and Japanese utility model laid open publication No. Sho.56-60911.

Although many mount arrangements are known as described above, there isstill a room for improvement in the arrangement of the various means onand/or in the vicinity of the mount members of the camera body andinterchangeable lens unit, particularly when the camera is to be adaptedto effect automatic diaphragm control and automatic focusing inaccordance with signals from the camera body.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide a mountarrangement of a photographic camera adapted to effect automaticdiaphragm control and automatic focusing in accordance with signals froma camera body, in which arrangement of members required for theautomatic diaphragm control and the automatic focusing and for thepositioning of an interchangeable lens unit relative to the camera bodyis improved over the prior arts and rationally determined.

Another object of the present invention is to provide an interchangeablelens unit for the photographic camera having the mount arrangement withthe above feature.

According to a mount arrangement of the present invention, there isprovided a bayonet mount device adapted to mount and demount aninterchangeable lens unit on and from a camera body throughpredetermined angle clockwise rotation and counterclockwise rotation ofthe lens unit relative to the camera body as viewed from the front ofthe camera, respectively. On the side of the lens unit, a positioningrecess is formed on an annular mount face of a lens unit mount member atan immediate life side portion of the lens unit mount member as viewedfrom the rear of the lens unit with the mounting of the lens unit on thecamera body completed, a driven shaft is provided on the mount face ofthe lens unit mount member at a lower left side portion of the lens unitmount member as viewed from the rear of the lens unit with the mountingof the lens unit on the camera body completed, electrical contacts areprovided at the inner peripheral side of an upper portion of the lensunit mount member with the mounting of the lens unit on the camera bodycompleted, and a diaphragm interlocked member is provided at the innerperipheral side of a left side portion of the lens unit mount member asviewed from the rear of the lens unit with the mounting of the lens uniton the camera body completed. The driven shaft is angularly spaced fromthe positioning recess by an angle larger than the predetermined anglefor the mounting and demounting of the lens unit on and from the camerabody. The electrical contacts are located rearwardly of the mount faceof the lens unit mount member and forwardly of the rear faces of bayonetclaws which are formed integrally with the lens unit mount member at arearmost portion of the lens unit while the diaphragm interlocked memberhas a rear end portion located rearwardly of the mount face of the lensunit mount member and forwardly of the electrical contacts. On the otherhand, on the side of the camera body, a positioning member to be engagedin the positioning recess is provided on an annular mount face of acamera body mount member at an immediate right wide portion of thecamera body mount member as viewed from the front of the camera body andurged to project from the mount face of the camera body mount member, adriving shaft to be coupled with the driven shaft for automatic focusingis provided on the mount face of the camera body mount member at a lowerright side portion of the camera body as viewed from the front of thecamera body, electrical contacts to be brought into contact with theelectrical contacts of the lens unit for signal transmission between thelens unit and the camera body are provided at the inner peripheral sideof an upper portion of the camera body mount member, and a diaphragmoperating member to be engaged with the diaphragm interlocked member forautomatic diaphragm control is provided at the inner peripheral side ofa right side portion of the camera body mount member as viewed from thefront of the camera body. The driving shaft is angularly spaced from thepositioning member by the same angle as the angular spacing between thedriven shaft and the positioning recess. The electrical contacts of thecamera body are located rearwardly of the mount face of the camera bodymount member so as to be brought into contact with the electricalcontacts of the lens unit with the mounting of the lens unit on thecamera body completed. The diaphragm operating member has a front endportion located forwardly of the electrical contacts of the camera bodyand rearwardly of the mount face of the camera body mount member so asto be engageable with the diaphragm interlocked member with the mountingof the lens unit on the camera body completed.

According to the present invention, the driven shaft and the positioningmember do not inferere with one another even in the state beforestarting the rotation of the lens unit for the mounting thereof on thecamera body because of the angular spacing as described above.Similarly, the diaphragm interlocked member and the electrical contactsof the camera body do not interfere with one another during the startand the course of the mounting of the lens unit on the camera body, dueto difference in their positions in the forward and rearward direction,i.e., in the direction of the optical axis of the lens unit.

The above and other features and advantages of the present inventionwill become more apparent from the following description of preferredembodiments of the present invention taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic rear elevational view of a mount portion of aninterchangeable lens unit at a mounting completed position, according toone preferred embodiment of the present invention,

FIG. 2 is a schematic front elevational view of a mount portion of acamera body according to the preferred embodiment of the presentinvention,

FIG. 3 is a schematic rear elevational view of the mount portion of thelens unit at a mounting starting position,

FIGS. 4 and 5 are fragmentary side sectional view of the mount portionsrespectively showing, in an enlarged scale, a positioning member and itsassociated mechanism,

FIG. 6 is a side sectional view showing a general construction of anautomatic focusing drive mechanism provided in the camera body,

FIG. 7 is a fragmentary side sectional view of the mechanism of FIG. 6showing a drawing shaft of the mechanism in a retracted state,

FIG. 8 is a schematic diagram explanatory of electrical contacts, andsignal feeding and reception between the interchangeable lens and thecamera body,

FIG. 9 is a schematic front elevational view of the camera body showingthe positional relationship between the electrical contacts and aflexible circuit board provided in the camera body,

FIG. 10 is a cross section taken along the line X--X in FIG. 1,

FIG. 11 is a cross section taken along the line XI--XI in FIG. 2, and

FIGS. 12 and 13 are rear elevational views of a mount portion of amodified interchangeable lens unit of the present invention at amounting completed position and a mounting starting positions,respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In preferred embodiments as illustrated, the present invention isapplied to a photographic camera employing a bayonet mount device whichis arranged to connect a mount member 1A of an interchangeable lens unitto a mount member 1B of a camera body through a clockwise rotation ofthe lens unit, and to disconnect the same through a counterclockwiserotation of the lens unit.

As shown in FIGS. 1 and 10, the mount member 1A of the lens unit has anannular mount face 2A centered at an optical axis 0, and three bayonetclaws 3A₁, 3A₂ and 3A₃ formed separately from one another at the rearside of the mount face 2A to radially outwardly project from a smalldiameter rear end portion of the mount member 1A. The bayonet claws arelocated at the rearmost position of the lens unit as shown in FIG. 10.It is to be noted here that FIG. 1 shows the state where the mountmember 1A of the lens unit is observed from the rear side of the lensunit in a posture in which mounting of the lens unit on the camera bodyhas been completed. In FIG. 1, there is formed a positioning groove orrecess 4A on the mount face 2A at the immediate left side lateralportion of the mount member 1A (i.e. at the immediate left side lateralportion of the mount member 1A as viewed from the front side of thecamera).

On the other hand, as shown in FIGS. 2 and 11, the mount member 1B ofthe camera body also has an annular mount face 2B centered at theoptical axis 0 and three bayonet claws 3B₁, 3B₂ and 3B₃ formedseparately from one another at the rear side of the mount face 2B toradially inwardly project from the inner peripheral portion of the mountmember 1B (any of the bayonet claws is not seen in the cross-section ofFIG. 11). The bayonet claws 3B₁, 3B₂ and 3B₃ are respectively engageblewith the bayonet claws 3A₁, 3A₂ and 3A₃ of the mount member 1A. In FIG.2 showing the state where the mount member 1B is observed from the frontside of the camera body, there is provided a positioning pin 4B on themount face 2B at the immediate right side lateral portion of the mountmember 1B. As shown in FIG. 4, this positioning pin 4B is urged by aspring 5 so as to project outwardly from the mount face 2B of the mountmember 1B in a direction of the optical axis for engagement in thecorresponding positioning groove 4A of the mount member 1A of the lensunit. The engagement of the positioning pin 4B in the positioning groove4A prevents the lens unit from rotating about the optical axis relativeto the camera body. Meanwhile, as shown in FIG. 5, when a release button6a of a release member 6 is depressed into the camera body, thepositioning pin 4B is retreated into the camera body so as to bedisengaged from the positioning groove 4A.

Referring again to FIG. 1 showing the state where the mount member 1A isobserved from the rear side of the interchangeable lens unit, on themount face 2A at a left side lower portion of the mount member 1A, thereis provided a driven shaft 7A of an automatic focusing drive mechanismwith its axis being directed in a direction of the optical axis. Here,on the assumption that a rotational angle, i.e. mounting rotationalangle required to complete the mounting of the interchangeable lens uniton the camera body as shown in FIG. 1 from the state of FIG. 3 isrepresented by θ, the distance of the driven shaft 7A from thepositioning groove 4A is set to be larger, in terms of a circumferentialrotational angle, than this rotational angle θ. This means that, whenthe mount member 1A of the lens unit is in the state before startingrotation for the mounting as shown in FIG. 3, the driven shaft 7A isbrought into a position deviated slightly towards the lower side fromthe position of the positioning pin 4B of the mount member 1B on thecamera body shown in FIG. 2.

Moreover, as shown in FIG. 2 on the mount face 2B, at the right lowerside portion of the mount member 1B of the camera body there is provideda driving shaft 7B of the automatic focusing drive mechanism with itsaxis being directed in the direction of the optical axis so that it canbe coupled with the driven shaft 1A when the mounting of the lens uniton the camera body is completed.

The spacing between the driving shaft 7B on the mount face 2B of themount member 1B and the positioning pin 4B should preferably be set at55° to 70° in terms of the circumferential rotational angle.

The general construction of the automatic focusing drive mechanismreferred to above is shown in FIG. 6. In FIG. 6, the lens unit isprovided with a lens 8 which forms a focusing optical system, a lensframe 9 which supports the lens 8, and a rack gear 9a formed at an outerperipheral portion of the lens frame so as to be in mesh with a wormgear 10 formed on the driven shaft 7A. The camera body is provided witha focus detecting means 11 which detects a deviation of the lens 8 fromthe in-focus position through measurement of light rays having passedthrough lens 8, and an automatic focusing control circuit 12 whichdrives a motor 13 in accordance with the amount and direction of thedeviation detected by the focus detecting means. The driving of themotor 13 is transmitted to a gear 14 of the driving shaft 7B through anappropriate transmission mechanism (now shown), thereby to rotate thedriving shaft 7B. The driving shaft 7B is urged by a spring 15 in thedirection of the optical axis so as to project outwardly from the mountface 2B of the mount member 1B. In the mounting completed state of thelens unit, the driving shaft 7B is coupled with the driven shaft 7A ofthe mount member 1A of the lens unit through engagement of engagingportions 7a and 7b formed on the confronting end faces of the drivenshaft and the driving shaft respectively, whereby rotation of thedriving shaft 7B is transmitted to the driven shaft 7A. Thus, throughthe meshing of the worm gear 10 with the rack gear 9a, the lens 8 isdisplaced toward the in-focus position. The camera body is furtherprovided with a lever 16 associated with a small diameter portion of thedriving shaft 7B. This lever 16 is also associated with the releasemember 6 described earlier and a change-over member (not shown) forchange-over between the automatic focusing mode and the manual focusingmode, so as to cause the driving shaft 7B to retreat toward the camerabody side against the spring 15 as shown in FIG. 7 when the releasemember 6 is depressed or when the change-over member is set to themanual focusing mode.

Along the inner peripheral side of upper portions of the mount member 1Aand the mount member 1B, a plurality of electrical contacts 17A and 17Bprovided in pairs are separately disposed, so that in the mountingcompleted state, the corresponding electrical contacts 17A and 17B arebrought into contact with each other. As shown in a schematic diagram ofFIG. 8, these electrical contacts 17A and 17B are intended to effectsignal transmission between a circuit 18 in the lens unit and a circuit19 in the camera body. The circuit 18 includes a ROM (read only memory)storing various signals inherent to individual lens units and requiredfor the automatic diaphragm control and the automatic focusing (forexample, a signal representative of a fully open aperture valve of thelens, and a signal representative of the amount of the shift of the lens8 per each rotation of the driven shaft 7A) and circuit means forselectively reading the signals from the ROM. The circuit 19 includes apower source, a clock pulse generator for generating clock pulses to befed to the circuit means in the circuit 18, an automatic diaphragmcontrol circuit and the automatic focusing circuit 12, etc. Most partsof the circuit 19 is formed by a CPU (central processing unit). In FIGS.1 and 2, numerals 20A and 20B represent electrically insulatingsubstrates provided with the electrical contacts 17A and 17Brespectively. These substrates are formed into an arcuate shapeextending along the inner peripheral sides of the mount members 1A and1B, and disposed in such a position retreated upwards from a rectangularpicture frame 21 of the camera body shown in one-dot-chain lines in FIG.2. Accordingly, the path of an effective light flux to expose a filmsurface through the picture frame 21 may be secured, with a harmfulreflected light not being readily produced. Meanwhile, as shown in FIG.9, a flexible circuit board 22 on which circuits of the camera bodyincluding the circuit 19 is formed and mounted is provided below anupper cover 23 of the camera body and above a pentagonal prism (notshown) without any conflict with a shutter dial and an ASA sensitivityor film speed dial on the upper cover and various display mechanismswithin a view finder. By the above arrangement, the electrical contacts17B are located in the vicinity of the flexible circuit board 2, withoutobstructing constructions of other members, whereby connections betweenthe electrical contacts 17B and the flexible circuit board 22 may bereadily effected in an efficient manner. The respective electricalcontacts 17A and 17B are provided with such sizes and disposingintervals therebetween that, under the mounting completed state,non-contact or erroneous contact may not take place due to looseness orside plays of the mount portions, and dimensional errors in the partsemployed, etc.

Furthermore, in FIG. 1 showing the state in which the mount member 1A isobserved from the rear side of the interchangeable lens unit, at theinner peripheral region of a left side portion of the mount member 1A(i.e., the right side portion of the mount member when observed from thefront side of the camera) there is provided a diaphragm interlockedmember 24A in the lens unit so that it is angularly spaced from theelectrical contacts 17A. The distance of the diaphragm interlockedmember 24A from the optical axis 0 is adapted to be close to thedistance of the electrical contacts 17A from the optical axis 0. In FIG.1, the diaphragm interlocked member 24A has a position shown by a solidline as a fully-open maximum diaphragm aperture position, and anotherposition 24A represented by a dotted line as a minimum diaphragmposition. Thus, the diaphragm interlocked member 24A is movable from thefully open aperture position to the minimum diaphragm aperture positionfor stopping down a diaphragm (now shown) provided in the lens unit.

Moreover, as shown in FIG. 2, at the inner peripheral side of a rightside portion of the mount member 1B of the camera body, there isprovided a diaphragm operating member 24B, so that it engages with thediaphragm interlocked member 24A under the mounting completed state.With respect to the diaphragm operating member 24B within the camerabody also, the distance of its position from the optical axis 0 isadapted to be close to the distance of the electrical contacts 17B fromthe optical axis 0. In FIG. 2, the diaphragm operating member 24B has aposition shown by a solid line as the fully-open diaphragm apertureposition, and another position 24B' denoted by a dotted line as aminimum diaphragm aperture position. It is to be noted that thediaphragm operating member 24B engaging the diaphragm interlocked member24A is normally held in the fully open diaphragm aperture position.However, upon start of a photographing operation, it is moved towardsthe minimum diaphragm position due to its stopping-down tendency,followed by the diaphragm interlocked member.

As shown in FIG. 10, in the disposition in the direction of the opticalaxis, the electrical contacts 17A of the lens unit are provided inposition closer to the camera body side than the mount face 2A of themount member 1A and closer to the mount face 2A than the rear surface ofthe bayonet claw 3A. In FIG. 10, a numeral 25 represents a decorativetube provided in the inner periphery of the mount member 1A, and betweenthis decorative tube 25 and the mount member 1A, the insulatingsubstrate 20A is held. At the outer peripheral portion of the decorativetube 25, a flexible circuit board 26 on which the circuit 18 is formedand mounted is provided for connection with the electrical contacts 17B.Represented by a numeral 27 is an IC in the circuit 18 provided with theROM. As shown in FIG. 11, in the disposition in the direction of theoptical axis, the electrical contacts 17B within the camera body aredisposed in position deviated rearwards, i.e., towards a predeterminedimage forming place (film plane) in the camera, from the mount face 2Bof the mount member 1B. In FIG. 11, the camera body is provided with aspring 27 which is disposed in an opening 28 of the insulating substrate20B for urging the electrical contacts 17B forwards in the direction ofthe optical axis. By the urging force of this spring 27, in the statewhere the interchangeable lens unit is disconnected from the camerabody, the electrical contacts 17B protrude forwards by a predetermineddegree beyond the position shown by an imaginary line in FIG. 11. As theelectrical contacts 17A of the lens unit in the mounting completed stateoccupy the position shown in the imaginary line, the electrical contacts17A and 17B are brought into contact with each other under the urgingforce of the spring 27. As the electrical contacts 17A and 17B are notdisposed at the rearmost position of the lens unit and at theforwardmost position of the camera body with respect to the opticalaxis, respectively, even when the lens unit and the camera body havingbeen disconnected from one another are placed with their mount membersdirected downwards respectively, the electrical contacts 17A and 17B donot abut on the placing surface, thus being free from any damages.

As shown in FIG. 10, the disposition of the diaphragm interlocked member24A of the lens unit in the direction of the optical axis is so set thatits rear end portion in the axial direction is positioned between themount face 2A of the mount member 1A and the electrical contacts 17A. InFIG. 10, a numeral 29 represents a diaphragm operating ring integralwith the diaphragm interlocked member 24A, and arranged to be rotatableabout the optical axis for stopping down the diaphragm aperture. Fittedover an outer periphery of a lens barrel 30 is a diaphragm presettingring 31 which is used to preset a diaphragm aperture, i.e., the maximumextent of the stopping down rotation of the diaphragm operating ring 29.As the diaphragm interlocked member 24A has a stopping tendency, thediaphragm operating ring 29 is rotated to a position to stop down thediaphragm aperture to the preset aperture value, when the lens unit isnot connected with the camera body.

As shown in FIG. 11, also with respect to the disposition of thediaphragm operating member 24B within the camera body in the directionof the optical axis, the setting is so made that its front end portionin the axial direction is located between the mount face 2B of the mountmember 1B and the electrical contacts 17B of the camera body. In FIG.11, the camera body is provided with a diaphragm aperture control ring32 integral with the diaphragm operating member 24B and arranged to berotatable about the optical axis for interconnection with a diaphragmaperture determining mechanism (now shown) within the camera body. Thediaphragm aperture determining mechanism stops the rotation of diaphragmaperture control ring 32 to stop the movement of the diaphragm operatingmember 24B and thus the movement of the diaphragm interlocked member 24Ain response to a diaphragm stop signal generated by the automaticdiaphragm control circuit upon achievement of a proper diaphragmaperture. Represented by a numeral 33 is a front frame of the camerabody provided, on its front face, with a fixed ring 34 to which themount member 1B is fixed. Between the diaphragm interlocked member 24Aand the diaphragm operating member 24B, a sufficient engaging margin asshown by a symbol W in FIG. 11 is provided in the mounting completedstate.

In the state before staring of the mounting, in which the mount member1A of the lens unit in the posture of FIG. 3 is inserted into the mountmember 1B on the camera in the posture of FIG. 2, if the diaphragmpresetting ring 31 is set at the fully-open diaphragm aperture value,the diaphragm interlocked member 24A in the lens unit is located at anupper region as indicated by a solid line in FIG. 3 so as to beoverlapped with the electrical contacts 17B on the mount member 18 ofthe camera body. However, the rear end portion of the diaphragminterlocked member 24A is located forwardly of the electrical contacts17A of the lens unit in the direction of the optical axis, so that thereis no possibility that the diaphragm interlocked member 24A of the lensunit and the electrical contact 17B of the camera body interfere witheach other during the starting and the course of the mounting thereofonto the camera body.

Incidentally, there are some interchangeable lens units which are notprovided with the diaphragm presetting ring 31. In the lens unit asdescribed above, the diaphragm interlocked member 24A is always stoppeddown to the minimum diaphragm aperture position shown by the numeral24A' in FIGS. 1 and 3, in the state before the mounting. Accordingly, itseems that there is no possibility that the member 24A and theelectrical contacts 17B overlap with one another even with the statebefore the starting of the mounting of the lens unit onto the camerabody. However, if the number of stages or steps for the stop-down fromthe fully-open diaphragm aperture to the minimum diaphragm aperture issmall, the minimum diaphragm aperture position of the diaphragminterlocked member 24A is not so far spaced apart from the fully-opendiaphragm aperture position as shown in FIGS. 12 and 13. Therefore, inthe state before starting the mounting as shown in FIG. 13, thediaphragm interlocked member 24A located at the minimum diaphragmaperture position 24A' comes to overlapped with the electrical contacts17B of the camera body, so that it becomes necessary to set thedisposition of the diaphragm interlocked member 24A in the direction ofthe optical axis in the same manner as described earlier, with respectto the lens unit having the diaphragm presetting ring 31.

In summary, the mount arrangement of the present invention has thefollowing advantages:

(a) Since the automatic focusing drive and driven shafts 7A, 7B areprovided on the mount faces 2A and 2B at the right side lower portionsof the mount members 1A and 1B as observed from the front side of thecamera, the driving motor 13 and the transmitting mechanism fortransmitting the drive force from the motor to the driving shaft 7B maybe readily disposed at a lower room space of the camera body.

(b) The electrical contacts 17A, 17B are disposed along the innerperipheral side of an upper portion of the mount members 1A and 1B toretreat upwards from the rectangular picture frame 21 of the camera bodywhile the diaphragm interlocked member 24A and the diaphragm operatingmember 24B are disposed at the inner peripheral side of a right sideportion of the mount members 1A and 1B to retreat rightwards from therectangular picture frame 21 as viewed from the camera front side, sothat the path of the effective light flux to expose a film surfacethrough the picture frame is readily secured, and harmful reflectedlight is not easily produced. Accordingly, there is no necessity toprovide a special light shielding treatment, etc. Moreover, since theseelectrical contacts 17A, 17B and diaphragm interlocked and operatingmembers 24A, 24B are spaced from the optical axis by substantially thesame distance, it is possible to mount on the camera body a largediameter lens unit with a short back focus and a large diameter rearlens, and even a ultra-telephoto lens unit with a small exist anglewithout interception of the effective light flux. Furthermore, it isgenerally required to provide some looseness or play between theradially facing fitting surfaces of the mount members 1A and 1B to allowsmooth attaching or detaching operations (see FIG. 11). Such loosenessmay result in increase in a positional error of the diaphragminterlocked member 24A in the circumferential direction as the distancefrom the diaphragm interlocked member 24A to the positioning recess 4Aincreases and the error become the maximum where the diaphragminterlocked member 24A is disposed diametrically opposite to thepositioning recess 4A. However, according to the present invention, thediaphragm interlocked member 24A is disposed close to the positioningrecess 4A, so that the error becomes small, resulting in improvement ofthe diaphragm aperture control accuracy.

(c) The electrical contacts 17A and 17B, the diaphragm interlockedmember 24A and the diaphragm operating member 24B are provided inpositions surrounded by the mount members 1A and 1B so as to beretreated in the lens unit and the camera body. Accordingly, under thestate where the lens unit is mounted on the camera body, these membersare completely covered or concealed by the mount members, so that theycan be protected from adhesion of dusts and dirts without addition ofany special protecting member. In addition, with the lens unit demountedfrom the camera body, the above members do not project out of the mountmembers 1A and 1B so that they are free from any damages if placedcarelessly on a desk. Accordingly, for the members 24A, 24B it is notrequired to take into account the case where unexpected loads or impactsapplied thereto, and they may be made of a material having a minimumstrength required for their original function (i.e., interconnectionbetween the rings 29 and 32). This means that the mass of members 24Aand 24B may be reduced, resulting in improvement of the diaphragmcontrol accuracy without retardation of the diaphragm aperturedetermination.

(d) Since the electrical contacts 17A and the diaphragm interlockedmember 24A are so set, in their disposition in the optical axisdirection, that, during the start and the course of the mounting of thelens unit onto the camera body, the electrical contacts 17A do notinterfere with the diaphragm interlocked member 24A. More freedom isassured in the designing of the number of electrical contacts, stroke ofthe diaphragm interlocked member per one stage of stop-down, and therotational angle for the amounting of the lens unit onto the camerabody.

(e) Since the angular spacing between the driven shaft 7A and thepositioning recess 4A and that between the driving shaft 7B and thepositioning member 4B are larger than the angle of the rotation of thelens unit for the mounting and demounting thereof on and from the camerabody, no interference occurs between the driven shaft 7A and thepositioning member 4B even in the state before the rotation of the lensunit for the mounting.

(f) At the inner peripheral side of a lower portion and a left portionof the mount members 1A and 1B as viewed from the front of the camera,there is left a room space sufficient for allowing disposition ofadditional signal transmitting and receiving members depending on needsin future.

What is claimed is:
 1. In a lens interchangeable photographic cameracapable of automatic diaphragm control and including a bayonet mountdevice which is adapted to mount and demount an interchangeable lensunit to and from a camera body through predetermined angle clockwiserotation and counterclockwise rotation of said lens unit relative tosaid camera body as viewed from the front of said camera, respectively,a mount arrangement comprising:a lens unit mount member fixedly providedon said lens unit, and having bayonet claws and an annular mount faceformed forwardly of said bayonet claws; a camera body mount memberfixedly provided on said camera body, and having an annular mount facelocated so as to be brought into contact with said mount face of saidlens unit mount member with the mounting of said lens unit on saidcamera body completed and bayonet claws formed rearwardly of said mountface of said camera body mount member so as to be engageable with saidbayonet claws of said lens unit mount member, said bayonet claws of saidlens unit mount member and said bayonet claws of said camera body mountmember constituting said bayonet mount device; a positioning recessformed on said mount face of said lens unit mount member at an immediateleft side portion of said lens unit mount member as viewed from the rearof said lens unit with the mounting of said lens unit on said camerabody completed; a positioning member provided on said mount face of saidcamera body mount member at an immediate right side portion of saidcamera body mount member and urged to project from said mount face ofsaid camera body mount member for engaging said positioning recess withthe mounting of said lens unit on said camera body completed; lens unitelectrical contacts having contact surfaces provided along the innerperipheral side of the upper portion of said lens unit mount member withthe mounting of said lens unit on said camera body completed, thecontact surfaces of said lens unit electrical contacts being arrangedrearwardly of said mount face of said lens unit mount member andforwardly of the rear faces of said bayonet claws of said lens unitmount member; camera body electrical contacts having contact surfacesprovided along the inner peripheral side of an upper portion of saidcamera body mount member, the contact surfaces of said camera bodyelectrical contacts being arranged rearwardly of said mount face of saidcamera body mount member so as to be brought into contact with thecontact surfaces of said lens unit electrical contacts with the mountingof said lens unit on said camera body completed for signal transmissionbetween said lens unit and said camera body; a diaphragm interlockedmember for the automatic diaphragm control, provided at the innerperipheral side of a left side portion of said lens unit mount member asviewed from the rear of said lens unit with the mounting of said lensunit on said camera body completed and having a rear end portionarranged rearwardly of said mount face of said lens unit mount memberand forwardly of the contact surfaces of said lens unit electricalcontacts; and a diaphragm operating member for the automatic diaphragmcontrol, provided at the inner peripheral side of a right side portionof said camera body mount member as viewed from the front of said camerabody and having a front end arranged rearwardly of said mount face ofsaid camera body mount member and forwardly of the contact surfaces ofsaid electrical contacts for said camera body, said rear end portion ofsaid diaphragm interlocked member and said front end portion of saiddiaphragm operating member being engageable with one another with themounting of said lens unit on said camera body completed.
 2. A mountarrangement as defined in claim 1, wherein said camera body includes arectangular picture frame and said camera body electrical contacts areretreated upwards from said rectangular picture frame while saiddiaphragm operating member is retreated rightwards from said rectangularpicture frame as viewed from the front of said camera body.
 3. A mountarrangement as defined in claim 2, further comprising:a manuallyoperable release member provided in the vicinity of said camera mountmember, and means for disengaging said positioning member from saidpositioning recess in response to a manual operation of said releasemember.
 4. A mount arrangement as defined in claim 2, wherein saidcamera body electrical contacts are urged forwards so as to be depressedagainst its urge by said lens unit electrical contacts with theconnection of said lens unit to said camera body completed.
 5. Aninterchangeable lens unit for use in a photographic camera capable ofautomatic diaphragm control and including a bayonet mount device whichis adapted to mount and demount said lens unit on and from a camera bodyof said camera through predetermined clockwise rotation andcounterclockwise rotation of said lens unit relative to said camera bodyas viewed from the front of said camera, respectively, said lens unitcomprising:a mount member fixidly provided on said lens unit and havingan annular mount face; bayonet claws provided integrally with said mountmember; a positioning recess located on said mount face at animmediate-left side portion of said mount member as viewed from the rearof said lens unit with the mounting of said lens unit on said camerabody completed; and electrical contacts for signal transmission betweensaid lens unit and said camera body, having contact surfaces provided atthe inner peripheral side of an upper portion of said mount member withthe mounting of said lens unit on said camera body completed, thecontact surfaces of said electrical contacts being arranged rearwardlyof said mount face and forwardly of the rear faces of said bayonetclaws; and a diaphragm interlocked member for the automatic diaphragmcontrol, provided at the inner peripheral side of a left side portion ofsaid mount member as viewed from the rear of said lens unit with themounting of said lens unit on said camera body completed, and having arear end portion arranged rearwardly of said mount face and forwardly ofthe contact surfaces of said electrical contacts.